Lecture 4 – Evolution 2.docx

Lecture 4 – Evolution 2.docx

Lecture 4 – Evolution 2
Introduction
­ Altruistic: helping others where there is no benefit and even harm to yourself
Example:
­ warning call when predator is in the area
­ animal giving the warning call draws attention to itself
“Selfish Gene” – natural selection will favor the genes and gene complexes that best
serve their own interest, namingly – replication
Cooperation – actor does a behavior that helps both him and another (can contribute
more to your own success than selfishness)
Selfishness – actor does a behavior that only benefits him and hurts the other
Cooperation = personal gain
­ teaching someone on your team to be a better player so you can win more games
­ what looks like a cost in the short run is actually a benefit in the long run
­ increasing the fitness of others can improve your own fitness
Adaptations aren’t for the good of the group; they are for the good of the gene
Increase in group’s success increases the “Helping gene”
Foraging in Groups
­ more animals to look for more food
­ being “vigilant” (checking surrounds) is important
­ the less you look up the more food you find
­ if all group members spend more timing searching for food and less time being
vigilant there will be more food for everyone
Problems with Altruism
Definition:
Altruism – behavior in which the actor incurs a cost to provide a benefit to a recipient
Not Altruism – foraging/vigilance groups (actor gains directly from behavior)
­ groups with altruism will benefit because group members are regularly helping
one another
­ an individual who performs altruistically decreases his own fitness but not a
selfish individual
Lemmings
­ live in far north
­ myth about suicidal population control
Inclusive Fitness
Eusocial Hymenoptera ­ includes all ants some bees and some wasps
­ most individuals spend their lives serving the colon without reproducing
W.D Hamilton
­ genes for altruism could be successful if they helped identical copies of
themselves
­ theory of “inclusive fitness”
Direct Fitness: fitness from personal reproduction
Indirect Fitness: fitness from the reproduction of close genetic relatives
Direct fitness + indirect fitness = inclusive fitness
­ Natural selection (because of inclusive fitness) can favor not only your behaviors
that increase an individual’s own reproductive success but also behaviors that
increase the reproductive success of close genetic kin
­ Shared genes between relatives can dive the evolution of altruism